Enhancing Labor Productivity of Selected Building Construction Operations Using Value Stream Mapping Integrated with Discrete Event Simulation
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Date
2020
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Addis Ababa University
Abstract
As a consequence of traditional managerial concepts, construction is characterized by a high share of non-value-adding activities (NVAA) and resultant low productivity. Labor productivity growth in the construction industry has averaged only 1% per year in the past 20 to 30 years. Likewise, the labor productivity of the Ethiopian construction industry is at the lowest level. This research offsets with the objective of measuring the level of NVAA and identifying their root causes using value stream mapping (VSM). Then it strives to enhance labor productivity by the application of lean concepts and principles using VSM integrated with discrete event simulation (DES).
Two case studies’, slab rebar and HCB operations, were selected and data were collected by observing the elapsed time of each sub-process and interviewing the manpower involved in the project. The developed VSM were used to analyze and measure the NVAA in the operations and propose the relevant lean concepts and principles. Subsequently, it was used to produce DES models in a detailed manner for the current state maps and exploration of different optimization scenarios.
The research outcome has revealed that 99.96 % and 99.7% of the slab rebar and HCB operations are constituted by NVAA, respectively. Moreover, from the current state VSM, the existence of a vicious circle of wastes has been witnessed and root causes related to the perspective of material and methods comprised the huge share. Workplace organization/ standardization (WOS), production scheduling (PS), and optimization of labor resources were found to be the most pertinent principles for both operations. The assessment of the scenarios using DES showed that labor productivity could be enhanced by 36.3 % and 34.6% for slab rebar and HCB operations, respectively. Correspondingly, the lead time improved by 95.9% and 49% for slab rebar and HCB operations. Finally, this research principally recommends project participants to give due attention to the flow dimension of construction and to identify and eliminate NVAA using VSM. Moreover, to adopt WOS, PS, and optimization of labor resources principles to enhance labor productivity and to integrate DES to comprehend the efficacy of the applied concepts and principles.
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Keywords
labor productivity, value stream mapping, lean concepts and principles, discrete event simulation, Simphony CYCLONE